Baseline Determination in Construction Labor Productivity-Loss Claims

Various ways of quantifying damages have been applied to productivity loss claims in construction. All of the ways attempt to be as objective as possible based on the extent of information available in a particular case. The measured mile, a widely accepted method, is employed when an unimpacted baseline period of production can be identified. Although that approach is considered to be the most objective method available in such cases, the method is limited and does not directly account for variation in individual productivity values about a normal or natural level of productivity. A gap exists between the use of existing methods and the availability of an appropriate methodology that specifically addresses variation in productivity. The key lies in the way baseline productivity is measured, which is inherently statistical, yet no truly statistical methods are used to establish such a baseline. Using the measured mile as a backdrop, this article provides an objective, measurement-based approach that can be used to establish a productivity baseline applied to construction productivity loss claims, based on the application of statistical methods aided by a process control chart. The focus is on providing the basic principles and concepts underlying the approach presented.     

KIRCHHOFF: an educational software for learning the basicprinciples and methodology in electrical circuits modeling

An interactive courseware package designed to be used as an auxiliary instructional tool by lower division students is described. The pedagogical goal of KIRCHHOFF is to foster mastery of basic methodological skills in the study of lumped electrical circuits. For a given circuit layout, proposed by the teacher, this is verified when the circuit has been systematically labeled and when a correct, complete and nonredundant set of algebraic and integro-differential equations has been written down by the student. KIRCHHOFF, a symbolic exercising tool, provides graphic guidance in such a process and, when needed, gives the learner suitable corrective explanations     

High performance liquid chromatographic separation of stereoisomeric bile acids as their UV-sensitive esters

High performance liquid chromatographic separation of a series of mono-, di- and trihydroxylated 5β-cholanic acids which differ only in position and configuration of hydroxyl groups at positions C-3, C-7 and/or C-12, is reported. The C-24 free acids were derivatized to four different classes of UV-sensitive esters, i.e.,p-bromophenacyl (BP),m-methoxyphenacyl (MP), 4-nitrophthalimidemethyl (NPM) and 9-anthrylmethyl (AM) esters, and chromatographed on two, variants of C₁₈ reversed-phase columns (Nova-Pak C₁₈ and Zorbax ODS) with methanol-water systems as mobile phase. Separation efficiency and elution order of some isomeric pairs were influenced by both the structure of the C-24 ester groups and the nature of the columns used. Excellent chromatographic properties were found for those derivatives, particularly for the NPM esters.     

Fabrication of Arsenic Sulfide Optical Fiber with Low Hydrogen Impurities

Arsenic sulfide glass optical fibers typically possess extrinsic absorption bands in the infrared wavelength region associated with residual hydrogen and oxygen related impurities, despite using purified precursors. We report a purification process based on the addition of tellurium tetrachloride (TeCl₄) to the glass. During melting, the chlorine from TeCl₄ reacts with the hydrogen impurities to produce volatile products (e.g., HCl) that can be removed by subsequent dynamic distillation. The processing conditions have been modified accordingly to produce optical fibers with significantly reduced loss due to hydrogen sulfide impurity content (1.5 dB/m).     

Air–steam leakage through cracks in concrete walls

In the context of a severe accident in a PWR nuclear plant, the evaluation of the leakage through the containment wall remains a key point of the safety analysis. Here we calculate the leakage of an air steam mixture through a traversing crack taking into account condensation. A 40 h test has been performed on a representative concrete slab with measurements of crack openings and flow rates. The CAST3M code enables us to simulate this test by making thermo-mechanical calculations and calculation of the leakage flow rate. Thermo-mechanical calculations provide data needed by the leakage calculations which are not measurable in the experiment. These are the internal crack profiles (variation of the opening with the curvilinear coordinate of the crack inside the concrete slab). Thermo-mechanical calculations are difficult to perform because boundary conditions of the test are complicated. Leakage calculations are performed with various hypotheses for the internal cracks profiles. A coefficient is applied on the friction factor to take into account additional complexity of the crack geometry.     

Plastic flow of polypropylene (PP) and PP-based blend

The evolution with temperature of the deformation mechanisms responsible for yielding in polypropylene (PP) and a PP-based blend is correlated to the molecular mobilities associated to glass transitions processes occurring in these materials. It is shown that the elementary local deformation event remains the same throughout the whole temperature range and that the onset of mobility only affects the average internal stress field \(\bar \sigma \) _i in which this thermally activated event takes place.     

A study of the apparatus function of a grid Fabry-Perot interferometer used as a F.I.R. spectrometer: Computing of the spectrum

Influences of various parameters on the apparatus function of a F.I.R. grid Fabry-Perot spectrometer are analysed. A pseudo-deconvolution method allowing an improvement of experimental results is tested by simulation and then applied to data concerning the isotopic HCl doublet at 41 cm^?1.     

Complement-Opsonized Nano-Carriers Are Bound by Dendritic Cells (DC) via Complement Receptor (CR)3, and by B Cell Subpopulations via CR-1/2, and Affect the Activation of DC and B-1 Cells

The development of nanocarriers (NC) for biomedical applications has gained large interest due to their potential to co-deliver drugs in a cell-type-targeting manner. However, depending on their surface characteristics, NC accumulate serum factors, termed protein corona, which may affect their cellular binding. We have previously shown that NC coated with carbohydrates to enable biocompatibility triggered the lectin-dependent complement pathway, resulting in enhanced binding to B cells via complement receptor (CR)1/2. Here we show that such NC also engaged all types of splenic leukocytes known to express CR3 at a high rate when NC were pre-incubated with native mouse serum resulting in complement opsonization. By focusing on dendritic cells (DC) as an important antigen-presenting cell type, we show that CR3 was essential for binding/uptake of complement-opsonized NC, whereas CR4, which in mouse is specifically expressed by DC, played no role. Further, a minor B cell subpopulation (B-1), which is important for first-line pathogen responses, and co-expressed CR1/2 and CR3, in general, engaged NC to a much higher extent than normal B cells. Here, we identified CR-1/2 as necessary for binding of complement-opsonized NC, whereas CR3 was dispensable. Interestingly, the binding of complement-opsonized NC to both DC and B-1 cells affected the expression of activation markers. Our findings may have important implications for the design of nano-vaccines against infectious diseases, which codeliver pathogen-specific protein antigen and adjuvant, aimed to induce a broad adaptive cellular and humoral immune response by inducing cytotoxic T lymphocytes that kill infected cells and pathogen-neutralizing antibodies, respectively. Decoration of nano-vaccines either with carbohydrates to trigger complement activation in vivo or with active complement may result in concomitant targeting of DC and B cells and thereby may strongly enhance the extent of dual cellular/humoral immune responses.     

Structures and morphologies of cast and plastically strained polyamide 6 films as evidenced by confocal Raman microspectroscopy and atomic force microscopy

Both confocal Raman microspectroscopy and atomic force microscopy (AFM) have been undertaken to study the crystalline and the morphological aspects of cast PA 6 films at a sub-microscopic scale. The percentages of the different crystalline structures present within PA 6 cast films, i.e. the monoclinic α, the pseudo-hexagonal β, and the monoclinic γ, have been measured by confocal Raman microspectroscopy. In cast films, the prevailing structure is the β one. AFM has been used to characterize the morphology of the PA 6 films. Simultaneously, the deformed state has been considered as well. Our main interest has been to follow the evolution of the percentage of each crystalline structure as a function of the plastic deformation mechanisms which are responsible of the yielding of PA 6 films: shear banding for temperatures T lower than 160 °C and formation of fibrils for      

Structure and functional complementation of engineered fragments from yeast phosphoglycerate kinase

Previous studies have shown that, although the isolated structuraldomains of yeast phosphoglycerate kinase recover a quasi-nativestructure in vitro as well as in vivo, they do not reassociatenor generate a functional enzyme. The aim of this work was firstto study the folding of complementary fragments different fromstructural domains and second to determine the requirementsfor their reassociation and functional complementation. Themethod used for producing rigorously defined fragments consistsof the introduction of a unique cysteinyl residue in the proteinfollowed by a specific cleavage by 5'5'-dithiobis(2-nitrobenzoate)/potassiumcyanide at this residue. Two pairs of complementary fragmentswere thus obtained, 1–96/97–415 and 1–248/249–415.The structure and stabilities of the different fragments werestudied. The short fragments, i.e. 1–96 and 249–415were found to contain some secondary structure, but to havea low stability. Each large fragment has a high structural contentand a stability close to that of the corresponding domain. Incontrast to that observed with the isolated domains, a weakbut significant complementation was observed for the two pairsof fragments; the pair of fragments 1–248/249–415recovered 8% of the activity of the native enzyme upon complementation.An independent refolding of the complementary fragments beforereassociation decreased the yield of complementation for thepair of fragments 1–96/97–415, but did not affectthe complementation for the other pair (1–248/249–415).From the present data and previous work on the isolated domains,it appears that the correct folding of the isolated fragmentsis not a prerequisite for their complementation.